{ "background": "Community health centres are a cornerstone of primary healthcare delivery in sub-Saharan Africa, yet robust evidence quantifying their impact on population-level health risk is limited. Existing evaluations often lack rigorous counterfactual comparisons.", "purpose and objectives": "This study aimed to estimate the causal effect of enhanced community health centre systems on composite health risk scores in a rural population, using a quasi-experimental design to address selection bias.", "methodology": "We employed a difference-in-differences design, exploiting the phased rollout of an integrated health centre strengthening programme across 120 villages. Household panel data were collected from 2,400 adults. The primary outcome was a validated composite health risk score (0-100). The core econometric model was: $Y{it} = \\beta0 + \\beta1 (Treati \\times Postt) + \\gamma X{it} + \\alphai + \\deltat + \\epsilon{it}$, where $\\alphai$ and $\\delta_t$ are individual and time fixed effects. Inference was based on cluster-robust standard errors.", "findings": "Exposure to the strengthened health centre system was associated with a significant reduction in mean health risk score by 7.3 points (95% CI: -10.1, -4.5). The largest risk reductions were observed in infectious disease and maternal-child health domains.", "conclusion": "The findings provide causal evidence that enhanced community health centres can effectively reduce population health risks. The quasi-experimental approach offers a viable methodology for impact evaluation in real-world, non-randomised programme implementation contexts.", "recommendations": "Policy should prioritise sustained investment in integrated community health systems. Future programme evaluations should incorporate quasi-experimental designs with longitudinal data to strengthen causal inference.", "key words": "health systems evaluation, quasi-experimental design, difference-in-differences, primary healthcare, causal inference, sub-Saharan Africa", "contribution statement": "This study provides novel causal evidence on the